1. Field
The present disclosure relates generally to the testing of components and in particular to a method and apparatus for performing non-destructive testing of components. Still more particularly, the present disclosure relates to a method and apparatus for non-destructive testing of components using transducers.
2. Background
Aircraft are being designed and manufactured with greater and greater percentages of composite materials. Some aircraft may have more than fifty percent of its primary structure made from composite materials. Composite materials may be used in aircraft to decrease the weight of the aircraft. This decreased weight may improve payload capacities and fuel efficiencies. Further, composite materials may provide longer service life for various components in an aircraft.
Composite materials may be tough, light-weight materials, created by combining two or more dissimilar components. For example, a composite may include fibers and resins. The fibers and resins may be combined to form a cured composite material.
In particular, key components, such as wings and fuselage skins, may be constructed with composite materials, such as, without limitation, a composite laminate. With more and more critical structures being made of composite laminates, methods and techniques to assure that these components meet quality standards are needed more than ever before.
Porosity may occur during processing to create composite components. Porosity may occur when voids form within a material. Currently, much time, effort, and money may be spent on non-destructive measurement systems designed to detect and quantify the porosity in composite components, such as those made using carbon laminates. These currently used techniques may take advantage of the fact that porosity does not block ultrasound signals but attenuates these signals. By measuring the amount of attenuation that occurs when transmitting an ultrasonic signal into a composite component, an estimate of the degree of porosity may be obtained for correlation with manufacturing specifications.
Many of the non-destructive measurement systems employ ultrasound transducers, which may be physical transducers. These types of transducers may require a coupling agent, such as a gel or liquid between the transducer and the sample. In some cases, using a coupling agent may be undesirable.
An electromagnetic acoustic transduction transducer may be used in these situations. These types of transducers may rely on eddy currents to transmit the vibration between the sample and the probe. This type of transducer, however, may not work well with poorly conducting materials, such as, without limitation, dielectrics found in composite materials. A dielectric may be a material that is highly resistant to the flow of an electric current. These types of material may contain carbon fiber and epoxy, which may not be good conductors.
In this situation, an electromagnetic transducer may be used with one or more conducting loops fixed to the sample to allow acoustic energy to be launched into and received from dielectric samples. These types of electromagnetic acoustic transducers, however, require a direct current magnetic field, which adds weight to the non-destructive measurement system. In using loops, time may be needed to attach the loops to the test sample, take measurements, and then remove the loops. Performing this process for each test sample may increase the time needed to test samples.
Therefore, it would be advantageous to have a method and apparatus for minimizing the need for contact with a component in performing non-destructive testing, which overcomes the problems discussed above.